Can keying sets be deleted in bulk?
Go to Dopesheet or Graph Editor, click on the little magnifier icon on the header bar, type in "Scale" in the input field, it will allow you to filter the channel by name. Then press A to select all channels (suppose you didn't have any customized name for other channel), X.

Even if you finally have some channels filtered that you do not want to delete, just try selecting or deselecting them with various selection tools, including single click. :)